Antidepressant stimulation of CDP-diacylglycerol synthesis does not require monoamine reuptake inhibition

<p>Abstract</p> <p>Background</p> <p>Recent studies demonstrate that diverse antidepressant agents increase the cellular production of the nucleolipid CDP-diacylglycerol and its synthetic derivative, phosphatidylinositol, in depression-relevant brain regions. Pharmacological blockade of downstream phosphatidylinositide signaling disrupted the behavioral antidepressant effects in rats. However, the nucleolipid responses were resistant to inhibition by serotonin receptor antagonists, even though antidepressant-facilitated inositol phosphate accumulation was blocked. Could the neurochemical effects be additional to the known effects of the drugs on monoamine transmitter transporters? To examine this question, we tested selected agents in serotonin-depleted brain tissues, in PC12 cells devoid of serotonin transporters, and on the enzymatic activity of brain CDP-diacylglycerol synthase - the enzyme that catalyzes the physiological synthesis of CDP-diacylglycerol.</p> <p>Results</p> <p>Imipramine, paroxetine, and maprotiline concentration-dependently increased the levels of CDP-diacylglycerol and phosphatidylinositides in PC12 cells. Rat forebrain tissues depleted of serotonin by pretreatment with <it>p</it>-chlorophenylalanine showed responses to imipramine or maprotiline that were comparable to respective responses from saline-injected controls. With fluoxetine, nucleolipid responses in the serotonin-depleted cortex or hippocampus were significantly reduced, but not abolished. Each drug significantly increased the enzymatic activity of CDP-diacylglycerol synthase following incubations with cortical or hippocampal brain tissues.</p> <p>Conclusion</p> <p>Antidepressants probably induce the activity of CDP-diacylglycerol synthase leading to increased production of CDP-diacylglycerol and facilitation of downstream phosphatidylinositol synthesis. Phosphatidylinositol-dependent signaling cascades exert diverse salutary effects in neural cells, including facilitation of BDNF signaling and neurogenesis. Hence, the present findings should strengthen the notion that modulation of brain phosphatidylinositide signaling probably contributes to the molecular mechanism of diverse antidepressant medications.</p

Effect of chemokine receptor CXCR4 on hypoxia-induced pulmonary hypertension and vascular remodeling in rats

<p>Abstract</p> <p>Background</p> <p>CXCR4 is the receptor for chemokine CXCL12 and reportedly plays an important role in systemic vascular repair and remodeling, but the role of CXCR4 in development of pulmonary hypertension and vascular remodeling has not been fully understood.</p> <p>Methods</p> <p>In this study we investigated the role of CXCR4 in the development of pulmonary hypertension and vascular remodeling by using a CXCR4 inhibitor AMD3100 and by electroporation of CXCR4 shRNA into bone marrow cells and then transplantation of the bone marrow cells into rats.</p> <p>Results</p> <p>We found that the CXCR4 inhibitor significantly decreased chronic hypoxia-induced pulmonary hypertension and vascular remodeling in rats and, most importantly, we found that the rats that were transplanted with the bone marrow cells electroporated with CXCR4 shRNA had significantly lower mean pulmonary pressure (mPAP), ratio of right ventricular weight to left ventricular plus septal weight (RV/(LV+S)) and wall thickness of pulmonary artery induced by chronic hypoxia as compared with control rats.</p> <p>Conclusions</p> <p>The hypothesis that CXCR4 is critical in hypoxic pulmonary hypertension in rats has been demonstrated. The present study not only has shown an inhibitory effect caused by systemic inhibition of CXCR4 activity on pulmonary hypertension, but more importantly also has revealed that specific inhibition of the CXCR4 in bone marrow cells can reduce pulmonary hypertension and vascular remodeling via decreasing bone marrow derived cell recruitment to the lung in hypoxia. This study suggests a novel therapeutic approach for pulmonary hypertension by inhibiting bone marrow derived cell recruitment.</p

Repeated Assessments of Informed Consent Comprehension among HIV-Infected Participants of a Three-Year Clinical Trial in Botswana

Informed consent (IC) has been an international standard for decades for the ethical conduct of clinical trials. Yet frequently study participants have incomplete understanding of key issues, a problem exacerbated by language barriers or lack of familiarity with research concepts. Few investigators measure participant comprehension of IC, while even fewer conduct interim assessments once a trial is underway.We assessed comprehension of IC using a 20-question true/false quiz administered in 6-month intervals in the context of a placebo-controlled, randomized trial for the prevention of tuberculosis among HIV-infected adults in Botswana (2004-2009). Quizzes were offered in both Setswana and English. To enroll in the TB trial, participants were required to have ≥ 16/20 correct responses. We examined concepts understood and the degree to which understanding changed over three-years. We analyzed 5,555 quizzes from 1,835 participants. The participants' highest education levels were: 28% primary, 59% secondary, 9% tertiary and 7% no formal education. Eighty percent of participants passed the enrollment quiz (Quiz1) on their first attempt and the remainder passed on their second attempt. Those having higher than primary education and those who took the quiz in English were more likely to receive a passing score on their first attempt (adjusted odds ratios and 95% confidence intervals, 3.1 (2.4-4.0) and 1.5 (1.2, 1.9), respectively). The trial's purpose or procedures were understood by 90-100% of participants, while 44-77% understood randomization, placebos, or risks. Participants who failed Quiz1 on their initial attempt were more likely to fail quizzes later in the trial. Pass rates improved with quiz re-administration in subsequent years.Administration of a comprehension quiz at enrollment and during follow-up was feasible in a large, international collaboration and efficiently determined IC comprehension by trial participants. Strategies to improve understanding of concepts like placebos and randomization are needed. Comprehension assessments throughout a study may reinforce key concepts